TriData , a Division of System Planning Corporation
3 . Improve Response Capacity : More Units on the Street
A Fire / EMS system must incorporate the necessary redundancies based on whether adjacent stations or units are likely to be available for emergency response . Below are guidelines that outline the redundancy levels needed to meet response time goals according to response levels and are based on our experience with workloads and how they affect availability .
• 1 . Very Low (< 500 responses / yr ) – Simultaneous calls are infrequent and unit availability usually is assured . Stations / units can be spaced at the maximum distance possible to achieve stated travel time objectives established by the community .
• 2 . Low ( 500-999 responses / yr ) – Few calls will overlap and unit availability usually is assured . Stations / units can be spaced at the maximum distance possible to achieve stated travel time objectives established by the community .
• 3 . Moderate ( 1,000-1,999 responses / yr ) – Some overlap of calls will occur , usually at peak demand periods ; however , stations / units are usually available . Stations / units must be located with marginal overlap to achieve stated travel time objectives established by the community .
• 4 . High ( 2,000-2,999 responses / yr ) – Additional overlap of calls will likely occur ; however , stations / units will probably be available for emergency response . Stations / units must be located with significant overlap to achieve stated travel time objectives established by the community . This footprint usually achieves the best results in terms of cost efficiency and effectiveness of service delivery . ( Overlap can be achieved with additional stations or additional units in existing stations .)
• 5 . Very High ( 3,000-3,999 responses / yr ) – Overlapping calls occur daily , usually during peak demand periods , and working incidents are frequent . The closest station / unit may not be available , thus requiring the response of adjacent stations / units . Stations / units must be located with the significant overlap to achieve stated travel time objectives established by the community . ( Overlap can be achieved with additional stations or additional units in existing stations .)
• 6 . Extremely High (> 4,000 responses / yr ) – Overlapping calls may occur hourly , regardless of the time of day . The closest station / unit is likely to be unavailable thus requiring the response of adjacent stations / units . Frequent transfers or moveups are required for the delivery system to meet demand . Stations / units must be located with redundancy ( back-up units ) to achieve stated travel time objectives established by the community . This footprint is usually found in very densely populated urban areas and is especially evident in EMS services located in urban areas with very high demand for service . ( Overlap can be achieved with additional stations or additional units in existing stations .)
The 3,000 – 3,200 response level ( very high category above ) is the point at which units are often considered “ busy ” and their availability needs to be evaluated . This is a rough rule of thumb , not a fixed standard . At this point , response times often will begin getting longer from frequent call overlap ( calls to the same first-due area arriving back-to-back ). As units become busier , the chances for overlap or simultaneous alarms increase , and second-due units begin to answer more calls . This causes a domino effect where unit B is dispatched to a call in unit A ’ s area because unit A is already engaged , causing unit B to be unavailable for the next call in its own area . Unit C must then respond to unit B or unit A ’ s area , and so forth .